There are numerous applications where it is necessary to penetrate a sealed container with a plurality of electrical leads so as to provide electrical access to and from electrical components enclosed within. One such application for which the present invention has particular but not limited utility is in body implantable pulse generators (e.g. for treatment of bradycardia, tachyaiythmia or for muscle or nerve stimulation), referred to generally as implantable pulse generators (IPG's). The heart pacemaker is a well known example of one type of IPG. Typical devices of this type are formed of a metal container housing the electrical and power source components of the IPG with a lid or the like welded to the container to close the device and provide it with a hermetic seal. An electrical lead is electrically connected to the IPG by means of attachment to one or more feedthroughs which penetrate the container but maintain the hermetically sealed environment thereof. A typical feedthrough consists of an external metal part (a frame or ferrule) into which preformed solid or sintered glass part is sealed. Within the glass part, one or more metal leads (pins) are sealed. Since the reliability of critical implantable medical devices depend on hermetic sealing of various components, the integrity of the glass to metal seals used in battery components and the seal between the internal electrical components and the human body is of paramount importance.
In many implantable medical devices, metals which have long term corrosion resistance and biocompatibility are needed to provide years of reliable service since maintenance or repair possibilities for the devices are extremely limited. Moreover, since such devices are sometimes lifesaving for the patient, failures of the feedthrough materials can have catastrophic consequences. Therefore, metals like titanium, niobium, tantalum, platinum and the like are used due to their well known superior corrosion resistance and biocompatability.
As such devices have undergone development, they have become smaller yet more electronically sophisticated, making it necessary to include more and more functions into smaller and smaller containers. This translates into a need for multi-pin feedthroughs carried by small, usually slim, containers. Multi-pin arrangements of feedthrough pins have generally been suggested before. For example, in U.S. Pat. No. 4,874,910 issued to McCoy, a number of flat pins are shown traversing a hermetic glass seal in a linear array. Or, in Neilsen et aL "Development of Hermetic Microminiature Connections", Journal of Elastomeric Packaging, Dec. 1991, Vol 113/405-409, the stresses on a compression seal for a multi-pin device are modeled. However, the successful combination of materials which include the corrosion resistance and biocompatibility required for an implantable medical device have not been disclosed.